Screen turns dark when the remaining battery is less than 5%. Why?

When the remaining battery is less than 5%, battery consumption is fast due to settings such as screen brightness and CPU. When the remaining battery is less than 5%,the phone will adjust screen brightnessto 0% to restrict use of unnecessary features

to improve the battery efficiency.

How to fix

Please be assured that it is a sign of normal operation. This feature has been offered for Optimus G Pro and later models.